Rheem 441 Series, 761 Series, 771 Series, 791 Series, 451 Series Service Instructions Manual

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Rheem Australia Pty Ltd ABN 21 098 823 511

SERVICE INSTRUCTIONS

Lazer 441, 451, 741, 751, 761,

771, 781 & 791 Series

TM001

Revision: AD

Issued: Jan 14

Lazer 1 & 2

Silhouette

(Designer Series)

Classic

(Modular Series)

Silhouette

(Modular Series)

441 Series

761 Series

771 Series

791 Series

451 Series

781 Series

741 Series

751 Series

First Issued: May 1987

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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CONTENTS

INTRODUCTION ..................................................................................................................... 3

SAFETY WARNING................................................................................................................. 3

MODEL IDENTIFICATION ....................................................................................................... 3

SPECIFICATIONS ................................................................................................................... 4

PREVENTATIVE MAINTENANCE .......................................................................................... 5

OPERATION ............................................................................................................................ 6

Electronic Controller Operating Modes ................................................................................. 6

COMPONENTS AND THEIR FUNCTIONS ............................................................................. 7

INSTALLATION NOTES .......................................................................................................... 8

WIRING DIAGRAMS ............................................................................................................... 9

741/751 (2.5L - 40L) ............................................................................................................. 9

761, 791 & 771/781 (2.5L – 40L) ........................................................................................ 10

FAULT FINDING .................................................................................................................... 11

General Fault Finding Chart ................................................................................................ 11

Mode 1 Fault Finding .......................................................................................................... 12

Component Tests 1 - 4 .................................................................................................... 13

Mode 2 Fault Finding .......................................................................................................... 14

Component Tests 5 - 8 ....................................................................................................... 15

Mode 3 & 4 Fault Finding .................................................................................................... 16

LAZER BOILING WATER UNITS AT HIGH ALTITUDES ...................................................... 17

How to Adjust the Temperature Setting of the Controller (ECB) ................................ ......... 17

ELECTRICAL IN-SERVICE TESTING ................................................................................... 18

ACCESSING COMPONENTS ............................................................................................... 19

COMPONENT REPLACEMENT ............................................................................................ 20

Water Temperature Sensor (Thermistor) ............................................................................ 20

DOCUMENT REVISION HISTORY ....................................................................................... 27

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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INTRODUCTION

The information provided in these instructions is based on the Rheem Lazer Boiling Water Unit being installed in accordance with the installation instructions provided with each unit.

Should you require further technical advice on the Rheem Lazer Boiling Water Unit, contact your nearest Rheem Australia Service Office where all genuine replacement parts are also available.

SAFETY WARNING

The purpose of this Service Manual is to provide sufficient information to allow a person with the skills as required by the controlling Regulatory Authorities to carry out effective repairs in the minimum of time.

Safety precautions or areas where extra care should be observed when conducting tests outlined in this service manual are printed in bold italics. Take care to observe the recommended procedure.

Certain diagnostic procedures outlined in these Service Instructions require

“live” testing of certain components. An RCD should be installed between the

power point and 3-pin cord of the water heater whilst conducting the tests.

MODEL IDENTIFICATION

The identification (model) number is designed to convey detailed information about the heater to which it is attached. Lazer Boiling Water Units are interpreted thus:

7 7 1

015

7 - Automatic Operation

4 & 7 - White enamel jacket 5 & 8 - S/Steel jacket 6 & 9 - Plastic Jacket, Silhouette

1 - Single heating unit 2 - Double heating unit

025 = 2.5 litre capacity 045 = 4.5 litre capacity 050 = 5.0 litre capacity 075 = 7.5 litre capacity 150 = 15 litre capacity 250 = 25 litre capacity 400 = 40 litre capacity

SERIAL NUMBER 741/751 Series

The serial number incorporates the date of manufacture as thus:

125

Month of Manufacture

Year of Manufacture

Serial Number

SERIAL NUMBER 771/781, 761 & 791 Series

The serial number indicates the country code AU for Australia and a sequential build number. The date of manufacture is listed on the rating plate inside the jacket by the month and year i.e. SEP 1999

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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SPECIFICATIONS

Capacity

Litres

Model

Heating Element

Input (kW)

Load & Wiring

Type

Electrical Supply

Inlet Water

Pressure (kPa)

Inlet & Outlet

Connection

Min

Max

2.5

741025

1 x 2.4

10 amp

3-pin plug

230/240 VAC

50Hz

1000

R½/15

771025

761025

791025

4.5

741045

1 x 2.4

10 amp

3-pin plug

230/240 VAC

50Hz

1000

R½/15

5.0

771050

1 x 2.4

10 amp

3-pin plug

230/240 VAC

50Hz

1000

R½/15

761050

791050

7.5

741075 751075

1 x 2.4

10 amp

3-pin plug

230/240 VAC

50Hz

1000

R½/15

771075 781075

761075

791075

741150 751150

1 x 2.4

10 amp

3-pin plug

230/240 VAC

50Hz

1000

R½/15

771150 781150

741250 751250

1 x 3.6

15 amp

circuit

230/240 VAC

50Hz

200

1000

R½/15

771250 781250

741400 751400

1 x 4.6

20 amp

circuit

230/240 VAC

50Hz

200

1000

R½/15

771400 781400

100

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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PREVENTATIVE MAINTENANCE It is suggested for peak performance that the Boiling Water Unit be serviced every six

months.

Servicing must be performed by suitably qualified persons.

Hot surface or liquid. Personal Protective Clothing (PPE) shall be worn to reduce the risk of burns or scalding.

1. Check the inlet strainer located inside the water inlet connection to ensure it is clean and not blocked with foreign matter. If an additional auxiliary filter is fitted, such as in areas of poor water quality check to ensure it is also clean and not blocked with foreign matter.

2. Check for signs of excessive corrosion on jacket and internal panels. Corrosion can be indicative that a leak is present.

3. Check for leaks at all BWU fittings.

4. Check the vent line to ensure it is not blocked with foreign matter. It is imperative that

the vent line does not become blocked as the BWU is not designed to be pressurised.

5. Isolate power and check all electrical connections for signs of overheating due to poor connection.

6. Conduct an electrical in-service test. (Refer to page 18).

7. Check tap for signs of leaking & excessive dripping after operation (clean or replace if required.

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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OPERATION IMPORTANT: High altitude will affect the Lazer Boiling Water Unit operation. Refer to

page 17 for more details To commission water heater from empty:

Turn on water supply first Turn on 240V supply, solenoid will open and filling will commence. Filling will continue until the water reaches the WLS low-level probe. Filling will stop and heating will commence until water reaches 97ºC. Heating continues and filling re-commences and continues until water temperature

drops to 93ºC. Each time the solenoid valve closes the WLS high level is checked.

This process repeats itself until the water level reaches the WLS high-level probe, at

which time the solenoid closes and the heating unit is switched off when water temperature reaches 97ºC.

From there on the heating unit will cycle to maintain water temperature between 93

and 97ºC.

The drawing off of boiling water will cause the solenoid to open and deliver cold water

on to the WTS which will in turn cause heating to commence.

The continuous drawing of water will cause the solenoid to close after 25 seconds;

ensuring water temperature is not continually reduced.

Electronic Controller Operating Modes Mode 1. Empty

When water level is below the WLS low-level probe the heating unit will turn OFF, and the solenoid valve will open to allow water to enter. When water level reaches the WLS low-level probe, a delay of 2 seconds will elapse before the solenoid closes and heating commences.

Mode 2. Not Full

Continuing from Mode 1, the heating unit will have power on throughout Mode 2. While it is heating, small quantities of water (approx. 100mL per cycle) are admitted through the solenoid each time the water temperature is sensed at 97ºC.

The solenoid will:

Open to fill at 97ºC Close at 93ºC

The solenoid cycle time will depend on the delay between cold-water entry and the sensing of 93ºC, which is directly related to:

Temperature of inlet water. Pressure of inlet water. Capacity of the Lazer Boiling Water Unit. Water level in the Lazer Boiling Water Unit

Water temperature should not drop below 93ºC throughout the fill cycle. Each time the solenoid closes, the WLS high- level probe is activated and, if found to be covered with water the ECB will change to Mode 3.

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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Mode 3. Full

When water has covered the WLS high-level probe the solenoid will close and heating will continue until a temperature of 97ºC is attained. The solenoid will open again for a split second at this time.

Thereafter the solenoid opens only when the water level falls below the WLS high- level

probe.

Heating will continue to cycle ON and OFF between 93 and 97ºC.

The drawing of water from the tap will return the ECB to Mode 2. During continuous drawing of water the solenoid will close after being open for 25

seconds.

Draining of all water will return the ECB to Mode 1.

Mode 4. Over temperature Cut Out (OTC)

The OTC mode will activate when the solenoid remains open for longer than 25 seconds in Mode 2.

Once activated the OTC will switch OFF power to the solenoid and heating unit and remain in this state until the water temperature drops below 93ºC. At this temperature the ECB will switch back to Mode 2.

The OTC mode is not temperature activated and will not prevent continuous boiling of the Lazer.

COMPONENTS AND THEIR FUNCTIONS ELECTRONIC CONTROL BOX (ECB): A box containing a transformer, relay and electronic

PC board which provides the logic to monitor and control water level and temperature. An over temperature function is incorporated to prevent the unit boiling dry. The wiring

terminals are 240 volt and 0 to 24 volt; therefore it is essential to connect all wires to the correct positions.

WATER LEVEL SENSOR (WLS): An insulated stainless steel probe that monitors:

Low water level to ensure the heating element cannot operate unless covered by

water

High water level to ensure the maximum water level is not exceeded.

Damage to the probe insulation will cause the heater to malfunction. SOLENOID VALVE / INLET FILTER: A 12-volt solenoid for 741/751 series with an inline

filter attached is located in front of the inner tank at the top of the water heater. A 24-volt solenoid for 761,771/781, 791 series with an inline filter attached is located on the

lower left hand side of the water heater. The operation is ON or OFF, but because of its small orifice size water hammer is not a

problem. HEATING UNIT / SENSOR PROBE: A square flanged heating unit, bent at 90º on some

units to suit the width of the tank, incorporating a sensor probe centrally located between the element loop.

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TEMPERATURE SENSOR (WTS): A thermistor is inserted inside the probe of the heating unit and monitors water temperature to maintain water at near boiling point.

OVERFLOW / VENT: The outlet of this pipe must be to atmosphere for the following reasons:

To allow air to escape while filling To allow excess water to escape To allow steam to escape while heating To prevent inner tank collapse when draining

INSTALLATION NOTES

The Lazer boiling water unit is not weatherproof. External locations must be protected from the weather and freezing conditions.

MOUNTING POSITION: Minimum clearances required for servicing are 350mm clear above the top and to the right for 741/751 series and 150mm clear above the top and to the right for 761, 771/781 and 791 series. Refer to installer to correct if clearances are less than required.

OVERFLOW/VENT: A drain line discharging to the atmosphere with a continuous fall, not exceeding 1 metre and with not more than 3 bends is required. The point of discharge should be where the user can see it, but not cause annoyance or injury if water or steam is discharged. A drain line not meeting these requirements must be installed with an air-break (tundish).

WATER SUPPLY: The Lazer Boiling Water Unit is not a pressurized appliance. An AIRBREAK is incorporated into the internal filler pipe. Connect only to a cold water supply with a constant pressure above the minimum supply pressure as specified in the SPECIFICATION TABLE on page 4.

The maximum supply pressure shall not exceed 1000kPa for all models. An approved stopcock is required for servicing purposes in the cold water supply line before the Lazer Boiling Water Unit.

IMPORTANT:

Non-return valves or stopcocks incorporating a non-return valve MUST NOT BE

INSTALLED in the water supply connection for 741, 751and 761 series. 771, 781 and 791 series have a non-return valve fitted within the water heater. DO NOT CONNECT TO A HOT WATER SUPPLY.

HOT WATER TAP: The tap is supplied with a chrome plated brass extension piece on 741/751 and 771/781 series. A 29mm A/F nut allows the tap to be aligned to a vertical position.

On 761 and 791 series the tap is a “Rocker” type and is already installed for use. The tap will drain all the contents of the Lazer Boiling Water Unit on some 741/751 series, and therefore expose the heating unit to the air.

DO NOT:

Over-tighten tap into tank. Remove the tap to service heating unit.

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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ELECTRICAL CONNECTION: All Lazer Boiling Water Units are designed for 220/240 volt 50 Hertz electrical supply. Installations that cannot achieve the specified supply current, i.e. private generators should be avoided. The internal wiring is designed to suit the load rating of the heating unit stated on the RATING LABEL found inside the jacket.

DO NOT FIT A HEATING UNIT OF HIGHER RATING THAN SPECIFIED ON THE

RATING LABEL.

Lazer Boiling Water Units with 10amp load are supplied with a 3-pin plug. A licensed electrician must wire units of 15amp capacity to a suitable supply.

WIRING DIAGRAMS 741/751 (2.5L - 40L)

2.5L -15L

25L - 40L

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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761, 791 & 771/781 (2.5L – 40L)

ECB

2.4kW Element

Solenoid

761- 791 - 771/781 Series

2.5L - 15L

Phase

Element

Neutral

Earth

Ready

Ground

Low

High

Solenoid-

Solenoid+

Sensor-

Sensor+

LED Board

P E N

Terminal Block

Note: ECO not fitted on 15L models

WLS

R B

761 & 791 models only

B/W

ECB

3.6kW - 25L

4.6kW - 40L Element

Solenoid

771/781 Series 25 - 40L

Phase

Element

Neutral

Earth

Ready

Ground

Low

High

Solenoid-

Solenoid+

Sensor-

Sensor+

P E N

Terminal Block

WLS

B/W

Relay

B=Black BL=Blue BR=Brown G=Green W=White R=Red B/W=Black/White

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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FAULT FINDING

It is possible to independently test individual components of the Lazer Boiling Water Unit, however it is strongly recommended that this Test Procedure be followed irrespective of a suspected malfunctioning component.

A failed or malfunctioning component may be the result of incorrect installation, faulty or intermittent services, i.e. large voltage or water pressure fluctuations, water filtration units or non-return valves in the water supply line or, incorrectly installed overflow/vent pipes.

Prior to commencing this Procedure ensure that the water pressure and electrical supply meet the required specification for the Lazer boiling water unit outlined on page 4.

General Fault Finding Chart

Disconnect power and

isolate water supply

Remove the jacket front or

access covers

Drain tank completely via drain

plug or tap

Water at elevated temperatures may be present when

draining, care should be taken to prevent scalding

Refit drain plug,

reconnect power and

restore water supply

Mode 1 diagnosis

YES

Mode 2 diagnosis

YES

Over temperature

mode diagnosis

YES

Mode 3 diagnosis

Normal OperationYES

Is the water

solenoid open?

Water solenoid closes

after a period?

Element

commences heating?

Solenoid alternates

operation until upper

water level reached,

element remains on

continuously?

Was the solenoid

open for longer than 25

seconds?

Mode 2 diagnosis

Element de-energized

after a period?

Element cycles to

maintain water

temperature?

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Mode 1 Fault Finding

YES YES

Repair broken strap or wiringNO

Disconnect the plug from the water level

probe

YES

Isolate power before checking

the water level probe connection

Clean connection or replace

wiring.

Retest operation

YES

Replace ECB

Retest operation

Clean or replace water level

probe

Restest operation

YES

Replace ECB

Retest operation

YES

Replace ECB and solenoid

valve

Retest operation

YES

Replace solenoid valve

Retest operation

Is the solenoid open? Does the solenoid close?

Mode 2 Diagnosis

Is there continuity of the

earth strap from the tank

to the ECB?

TEST 1

2.1

Does the solenoid open?

Is the connection to the water level probe clean

and tight?

Is scale built up on probe

wires or body?

TEST 2

Is the supply voltage from

the ECB correct?

TEST 3

Is the resistance of the

solenoid valve correct?

TEST 4

Mode 2 Diagnosis

Is the resistance of the solenoid valve correct?

TEST 4

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Component Tests 1 - 4

Test 1

Test 2

Normal resistance between the tank and the earth point on the ECB is 0 ohms (dead short) when measured with a multimeter on the x1 resistance scale.

Normal resistance between the high level probe wire and low level probe wire should be infinity (open circuit) when measured with a multimeter on the x10M resistance scale.

Test 3

Test 4

Install RCD and exercise caution when

conducting live tests

741/751 series

Normal voltage at the solenoid under load should be between 6 and 12 volts when measured with a multimeter on the DC voltage scale.

761, 771/781 and 791 series

Normal voltage at the solenoid under load should be between 8 and 24 volts when measured with a multimeter on the DC voltage scale.

741/751 series

Normal resistance of the solenoid coil should be 23 ohms +/- 5% when measured with a multimeter on the x1 resistance scale.

761, 771/781 and 791 series

Normal resistance of the solenoid coil should be 55 ohms +/- 5% when measured with a multimeter on the x1 resistance scale.

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Mode 2 Fault Finding

YES

Replace solenoid

Retest operation

Replace element Retest operation

YES

Replace thermistor

Retest operation

YES

Refit the thermistor in the

correct position

Retest operation

Adjust the temperature setting by following the potentiometer

procedure in this manual.

Retest operation if fault

persists replace the ECB

YES

Replace ECB

Retest operation

2.5, 5 & 7.5 litre models

Replace relay

Retest operation

YES

15, 25 & 40 litre models

Is voltage present

at the element?

TEST 5

Capacity of Lazer?

Is voltage

present at relay?

TEST 6

Has the

Solenoid closed?

Is the resistance

of the element correct?

TEST 7

2.2

Does the unit

boil continuously?

2.1 3

Does the solenoid close

when upper water level

reached?

Is the resistance of

the thermistor correct?

TEST 8

Is the thermistor fully

inserted into the well?

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Component Tests 5 - 8

Test 5

Test 6

Install RCD and exercise caution when

conducting live tests

Normal voltage at the element is 240v when measured with a multimeter on the AC voltage scale

Install RCD and exercise caution when

conducting live tests

Normal voltage to the relay coil is 240v when measured with a multimeter on the AC voltage scale.

Test 7

Test 8

Normal resistance of the element and ECO when measured with a multimeter on the x1 resistance scale is:

2.4kW - 23.7 ohms +/- 5%

3.6kW - 15.7 ohms +/- 5%

4.6kW - 12.3 ohms +/- 5%

Normal resistance of the water temperature sensor (Thermistor) is 950 ohms - 1000 ohms at 20ºC. The Thermistor should be replaced if the reading is less than 850 ohms or greater then 1250 ohms. When measured with a multimeter on the x1K scale a normal reading will be between .95 and 1.00.

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Mode 3 & 4 Fault Finding

Any time the solenoid is open

for a period exceeding 25

seconds before a shift in

temperature is detected the

unit will enter the over

temperature mode (OTC)

YES

Check for low supply flow due

to water filters etc

Advise customer to draw

smaller quantities of water at

one time

Replace solenoid

Retest operation

YES

Check the water level probe

sensor wires for correct length

Siphoning may be occurring.

Advise user to have a tundish

installed as per the installation

instructions.

Unit may enter over temperature (OTC) mode during this condition if the

solenoid opens for periods

exceeding 25 seconds

YES

OTC MODE

Draw a quantity of water from

the unit through the tap

Normal OperationYES

Are large quantities of hot

water being discharged

from the vent pipe?

Is the vent pipe

longer than 3 metres?

Does the unit discharge

large quantities of hot

water intermittently?

Does the unit maintain

water temperature during

periods of non use?

Did the unit

Refill and heat?

2.2

Are large amounts

of hot water being drawn

through the tap?

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LAZER BOILING WATER UNITS AT HIGH ALTITUDES

An increase in altitude will reduce the boiling temperature of water. Therefore it is necessary to provide an adjustment on the Lazer Control System for installations over 300 metres above sea level.

All controllers supplied as a component of the finished product are factory adjusted to deliver water at a temperature of 92ºC.

Why should temperature adjustment be necessary?

Replacement of the Electronic Controller Replacement of the Thermistor or a Heating Unit and Thermistor. Altitude compensation

Where is the Adjustment Potentiometer and what does it look like?

Relative to the controller terminals, the Potentiometer (Trim Pot) for temperature adjustment is located at the right rear of the control box. Access is provided by means of a 10mm diameter hole in the controller cover (refer to figure below). Some controllers have no covers fitted, so the Trim Pot is visible on the PCB at the described location.

The Trim Pot can be identified as being a white or blue disc, approximately 6mm in diameter and having a screw driver slot in its top face.

The dotted lines of the TRIM POT arc

represent “HOURS”.

Each hour represents approx 1ºC

How to Adjust the Temperature Setting of the Controller (ECB)

Components adjacent to the trim pot will be live, take care while making adjustments not to touch other components.

1. Isolate the electrical supply and drain the Lazer Boiling Water Unit to a low level.

2. Using a 3mm wide screw driver, rotate the Trim Pot ANTICLOCKWISE to its MINIMUM SETTING.

3. Switch the power back ON and allow it to operate automatically for 5 MINUTES (the element should switch on and the solenoid valve should operate at least once).

4. Using a 3mm wide screw driver, rotate the Trim Pot CLOCKWISE to its MAXIMUM SETTNG. The unit will now boil and not take water.

5. Allow the unit to boil for approx. 1 minute before rotating the Trim Pot ANTICLOCKWISE until such time as the solenoid opens, allowing water to flow into the tank.

6. Rotate the Trim Pot ANTICLOCKWISE a further turn (approx. 45 degrees). This will prevent the unit from boiling should atmospheric pressure decrease.

7. Before re-fitting the jacket cover wait at least one solenoid operation to ensure that the unit has been correctly adjusted.

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ELECTRICAL IN-SERVICE TESTING

Wear Personal Protective Equipment when conducting step 1 of these procedures to reduce the risk of electric shock. Refer to Rheem safety procedure on electrical testing.

1. For 3 – 15L models: Isolate power by switching off at power point and unplugging

BWU 3 pin plug from power point. For 25 & 40L models: Isolate power by turning isolation switch off and then

removing fuse (or switching off circuit breaker). Disconnect Active, Neutral and Earth wires from BWU terminal block.

Procedure 1: To check insulation resistance of the BWU Neutral Circuit (reading not to be below 1 mega-ohm).

2. For 3 – 15L models: Connect megger leads to the neutral and earth pins on the 3-pin

plug. For 25 & 40L models: Connect megger leads to the Neutral conductor and the Earth

terminal of the BWU terminal block.

3. Operate insulation resistance tester. A reading above 1 mega ohm should be obtained.

4. If a reading below 1 mega ohm is indicated, all component parts will need to be

individually tested to locate the fault.

Procedure 2: To check insulation resistance of the BWU Active Circuit (reading not to be below 1 mega-ohm).

5. For 3 – 15L models: Connect megger leads to the active and earth pins on the 3-pin plug.

For 25 & 40L models: Connect megger leads to the active conductor and the earth terminal of the BWU terminal block.

6. Operate insulation resistance tester. A reading above 1 mega ohm should be obtained.

7. If a reading below 1 mega ohm is indicated, all component parts will need to be

individually tested to locate the fault.

Procedure 3: To check “Earth Continuity” of the water heater.

8. Set the multimeter to x1 Ω (ohms) resistance scale.

9. (3 – 15L Models) Measure between the earth pin on the 3 pin plug and the water heater

jacket. The reading should be less than 0.5Ω. (25-40L models) Measure between the earth terminal and the water heater jacket. The

reading should be less than 0.5Ω.

10. If a reading greater than this value is obtained the earthing connection should be checked

for corrosion/tightness and the power lead earth wire tested, if necessary replace the power lead.

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ACCESSING COMPONENTS

Ensure that the unit is unplugged or isolated from the electrical supply.

Removing & Replacing Jacket Lid and Name Plate

(741/751 Series)

Removing the Lid (Figure 1)

1. Remove the four retaining screws.

2. Remove the LID by lifting from the jacket.

Figure 1

Removing the Nameplate (Figure 2)

1. Remove the two retaining screws.

2. Slide the Nameplate forward on the Tap Stem and rotate through 90 degrees to obtain access to components.

Note: The Tap does not need to be removed to service or replace components housed behind the Nameplate.

Figure 2

Removing & Replacing Jacket Front

(761 and 791 Series)

Removing the Jacket Front (Figures 3&4)

1. Remove the two retaining screws. (Figure 3)

2. Remove the spout by pulling down and gently pushing toward the back.

Figure 3

3. Insert fingertips between the Jacket Front and Jacket Back in the vicinity of the Jacket Retaining Clips and gently pull the Jacket Front forward until free of tap. (Figure 4)

4. Lift the Jacket Front until free of the Retaining Clips.

Warning: The LED Display lead (item 1, figure 4) must now be disconnected from the ECB. The Jacket Front is then free to be removed.

Figure 4

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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COMPONENT REPLACEMENT

Water Temperature Sensor (Thermistor)

Ensure that the unit is unplugged or isolated from the electrical supply.

741/751 Series

1. Remove the nameplate. (Refer to page 19)

2. Disconnect the wiring to the water temperature sensor.

3. Withdraw the water temperature sensor from the element.

4. Coat the thermistor with “heat sink compound”

5. Slide the replacement water level sensor into the element ensuring it seats at the end of the tube.

6. Reconnect the wiring and refit the nameplate.

7. Restore power and test operation of boiling water unit.

Figure 5

761, 771/781 & 791 series 2.5L – 7.5L

1. Remove the jacket front.

2. Disconnect the wiring to the water temperature sensor.

3. Withdraw the water temperature sensor from the element.

4. Coat the thermistor with “heat sink compound”

5. Slide the replacement water level sensor into the element ensuring it seats at the end of the tube.

6. Reconnect the wiring and refit the nameplate.

7. Restore power and test operation of boiling water unit.

771/781 series 15L – 40L

1. Remove the left hand side panel. (Refer to figure 9 page 22)

2. Disconnect the wiring to the water temperature sensor.

3. Withdraw the water temperature sensor from the element.

4. Coat the thermistor with “heat sink compound”

5. Slide the replacement water level sensor into the element ensuring it seats at the end of the tube.

6. Reconnect the wiring and refit the nameplate.

7. Restore power and test operation of boiling water unit.

Figure 6

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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Electronic Control Box

Ensure that the unit is unplugged or isolated from the electrical supply.

741/751 Series

1. Remove the Jacket Top (Refer to page

19)

2. Gently disconnect the push-on spade terminals

3. Slide the ECB upwards to disengage from the metal tabs in the back panel and lift the ECB clear.

4. Replace the ECB repeating the above steps in the reverse. Ensure that the wiring loom terminals are correctly replaced. Check the terminal block connector to ensure that no wires were accidentally dislodged during the service repair.

5. Restore the power supply and test the unit for normal operation.

6. Refit the Jacket Top.

Figure 7

761, 771/781 and 791 Series

1. Remove the Jacket Front, 2.5L – 7.5L (Refer to page 19) or Left hand side panel, 15L – 40L (Refer to figure 9 page 22).

2. Gently disconnect the push-on spade terminals and the multi-pin connector from the ECB.

3. With the aid of fingertips, gently unclip the ECB Mounting Clips (3) clear of the controller board and lift the ECB (4) through 40 degrees as shown in figure 6.

4. Remove the ECB from the rear Mounting Clips by pulling forward.

5. Replace the ECB repeating the above steps in the reverse. Ensure that the wiring loom terminals are correctly replaced. Check the terminal block connector to ensure that no wires were accidentally dislodged during the service repair.

6. Restore the power supply and test the unit for normal operation.

7. Refit the Jacket Front or Top.

Figure 8

NOTE: ALWAYS check product EARTHING before replacing the Jacket Front or Top

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Solenoid Valve

Ensure that the unit is unplugged or isolated from the electrical supply and the stopcock is closed.

761, 771/781 and 791 Series

1. Remove the Jacket Front (2.5L - 7.5L models, refer to page 19) or Side Panel (15 - 40L models, refer to figure 9)

2. Disconnect the push-on spade terminals from the solenoid

3. Disconnect the inlet supply pipe to the unit.

4. Disconnect the silicone tube

5. Hold the inlet fitting with the aid of a 24mm AF spanner and, using a 27mm AF spanner remove the retaining nut.

6. Remove the Nylon Washer

7. Remove the valve and inlet assembly from the tank.

8. Unscrew the valve assembly from the inlet fitting.

9. Reassemble the inlet fitting, nylon washer and replacement valve assembly.

10. Refit the assembly in reverse order of above.

11. Restore water supply and check for water leaks.

12. Refit panels, restore power supply and test unit for normal operation.

Figure 9

741/751 Series

1. Remove the jacket top (Refer to page 19)

2. Disconnect the solenoid lead spade connectors from the ECB.

3. Place absorbent cloth below and around solenoid to protect ECB and wiring from water spillage.

4. Hold the solenoid securely and undo the compression nuts on either side of the valve assembly.

5. Remove the solenoid valve assembly.

6. Fit the replacement solenoid valve assembly ensuring the water flow is in the direction of the arrow on the brass body.

7. Complete assembly in reverse order of above.

8. Restore water supply and check for water leaks.

9. Refit panels, restore power supply and test unit for normal operation.

Figure 10

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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Water Level Probe

Ensure that the unit is unplugged or isolated from the electrical supply and the stopcock is closed.

A common Water Level Probe is supplied as a replacement part. Prior to fitting the probe it may be necessary to cut the long and short sensor wires to suit the model. Refer to the table on page 24 for correct cutting lengths.

741/751 and 771/781 Series Removing the Water Level Probe

1. Remove the jacket top, all 741/751series and 771/781 series 15l –40L, or jacket front, 771/781 series 2.5L – 7.5L. (Refer to page 12)

2. Disconnect the wiring connector from the Water Level Probe.

3. Remove the Water Level Probe by pulling vertically out of the tank (Exercise care not to distort the tank top).

Replacing the Water Level Probe

1. Bend the high level probe wire (item 3, figure 11) away from the low level probe wire (item 4, figure 11) to an angle of 15º, or such that slight pressure is needed to squeeze the probe wires together when inserting the Water Level Probe into the tank sleeve.

2. Insert the replacement Water Level Probe into the tank sleeve and press until seated. (Exercise care not to distort the tank top.)

3. Refit the wiring connector to the Water Level Probe

4. Restore water and power supplies, check for water leaks and test boiling water unit for correct operation.

5. Refit the jacket top or front.

Figure 11

761 and 791 Series Removing the Water Level Probe

1. Remove the jacket front. (Refer to page 19)

2. Disconnect the wiring connector from the Water Level Probe

3. Remove the Water Level Probe by pulling vertically out of the tank. (Exercise care not to distort the tank top.)

5. Bend the high level probe wire (item 3, figure 12) away from the low level probe wire (item 4, figure 12) to an angle of 15º, or such that slight pressure is needed to squeeze the probe wires together when inserting the Water Level Probe into the tank sleeve.

6. Insert the replacement Water Level Probe into the tank sleeve and press until seated. (Exercise care not to distort the tank top.)

7. Refit the wiring connector to the Water Level Probe

8. Restore water and power supplies, check for water leaks and test boiling water unit for correct operation.

9. Refit the jacket front.

Figure 12

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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Water Level Probe Lengths

Cut each leg of the Water Level Probe to the length shown in the table below

Model

Short Probe Length in mm

(Length X)

Long Probe Length in mm

(Length Y)

741025

112

137.5

741045

112

262.5

741075 / 751075 741150 / 751150 741250 / 751250

112

367.5

741400 / 751400

112

582

761025

112

200

761050

112

273

761075

112

390

771025

100

205

771050

100

290

771075 / 781075

100

390

771150 / 781150 771250 / 781250 771400 / 781400

100

465

791025

100

205

791050

100

290

791075

100

390

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Element

Ensure that the unit is unplugged or isolated from the electrical supply and the stopcock is closed. Water at elevated temperatures may be present when draining, care should be taken to prevent scalding.

741/751 Series

1. Drain the Lazer boiling water unit

2. Remove the Nameplate. (Refer to page 19)

3. Disconnect the 2 wires from the element terminals.

4. Disconnect the wiring to the water temperature sensor.

5. Undo the 2 retaining nuts from the element flange and remove the element.

6. Replace element gasket if required.

7. Reassemble in the reverse order of above.

8. Restore water and power supplies and allow unit to fill and heat.

9. Check for water leaks

10. Refit nameplate. Disconnect power during this step.

761, 771/781 and 791 series

2.5L – 7.5L

1. Drain the Lazer boiling water unit.

2. Remove the Jacket Front. (Refer to page 19)

3. Disconnect wire from element terminal and ECO.

4. Disconnect the wiring to the water temperature sensor.

5. Undo the 2 retaining nuts from the element flange and remove the element.

6. Replace element gasket if required.

7. Reassemble in reverse order of above.

8. Restore water and power supplies and allow unit to fill and heat.

9. Check for water leaks.

10. Refit the Jacket Front. Disconnect power during this step.

15L – 40L

Follow the procedure outlined above, removing the left hand side panel (Refer to figure 9 page 22) not the jacket front at step 2.

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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Tap

741/751 & 771/781 Series

1. Drain the Lazer boiling water unit.

Tap head only

2. Using a spanner undo the lock nut at the tap head.

3. Remove the tap head.

4. Fit the replacement tap, ensuring it is vertical when retightening the lock nut

5. Restore water and power supplies and test boiling water unit operation

Complete Tap Assembly

2. Grip the tap extension with multigrips (or similar) and unscrew the tap assembly from the tank. Care should be taken not to damage or distort the tank.

3. Apply Teflon thread tape to the replacement tap extension and screw into the tank. Care should be taken not to damage or distort the tank. (A barrier such as a piece of cloth should be wrapped around the replacement tap extension to prevent damage to the finish of the shaft by tools)

4. Ensure the tap head is vertical; loosening the tap head lock nut will allow adjustment of the tap head position.

5. Restore water and power supplies and boiling water unit operation.

Figure 13

761/791Series

1. Drain the Lazer boiling water unit

2. Remove the jacket front. (Refer to page 19)

3. Unscrew the lock nut (anti-clockwise) and gently pull the tap assembly from the tap body.

4. Carefully insert the replacement tap assembly into the tap body and tighten the lock nut (clockwise). Note: Do not over tighten, as this will cause the tap to drip.

To replace the spring, lightly compress the spring by pressing on the front of the diaphragm. This will facilitate the removal of the tap cap pin to allow the tap to be disassembled.

Figure 14

Note: The tap seal and spring are replaceable as separate items. Refer to Spare Parts Manual SPM-BW for part numbers.

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Service Instructions REV AD. Issue 02/01/14

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DOCUMENT REVISION HISTORY

Title:

Lazer 441, 451, 741, 751, 761, 771, 781 & 791 Series Service Instructions

Document No:

TM001

Rev

Details of change

D.O.I.

Service Instructions issued for 441/451 series Lazer

05/87

Service Instructions updated to cover 741, 751, 771, 781, 761 & 791 series Lazer

27/04/01

Reference to Southcorp replaced by Rheem Australia

28/03/03

Format updated; Warranty Statement removed; Exploded views & Replacement Parts Lists removed, now form part of Boiling Water Spare Parts Manual SPM-BW

02/01/14

NOTE: Every care has been taken to ensure accuracy in preparation of this publication. No liability can be

accepted for any consequences which may arise as a result of its application.

Rheem 441 Series, 761 Series, 771 Series, 791 Series, 451 Series Service Instructions Manual

Specifications and Main Features

Frequently Asked Questions

User Manual